All data used in this paper are publicly accessible.
(1) Beijing PM2.5. http://www.stateair.net/web/historical/1/1.html
(2) NCEP Reanalysis. https://www.esrl.noaa.gov/psd/data/gridded/data.ncep.reanalysis.html
(3) In-situ meteorological data. https://data.noaa.gov/dataset/dataset/global-surface-summary-of-the-day-gsod
(4) SST and sea ice. https://www.metoffice.gov.uk/hadobs/hadisst/
